Development of the imaging system to evaluate of blood flow distribution and metabolic activity in myocardial microcirculation.

构建了心肌代谢活动和血流分布的荧光显微镜成像系统。为了在体内条件下用活体视频显微镜测量微循环中的红细胞速度，开发了新的软件。在时间序列录像图像中沿毛细血管设置线段，然后沿该线段构造时空图像。估计时空图像中反映红细胞速度的条纹图案的角度，计算红细胞速度矢量映射。我们成功地利用视频显微镜系统和时空图像分析方法对体内微循环进行了定量评价。区域心肌对缺氧的易感性是不均匀的；然而，局部缺氧的动力学以及局部缺氧对血流异质性的依赖尚不清楚，特别是在微循环水平上。因此，我们在氧合的逐步变化过程中评估了心肌外膜NADH荧光，并对NADH荧光和血流分布进行了比较，将其分解为0.1×0.1-至0.4×0.4-mm^2区域，其大小与单个毛细血管前小动脉灌注的微循环单元相当。在另一个低氧灌注的心脏中，显示稳定的斑片状荧光模式，注入氚标记的去甲基咪唑胺，并通过数字x线摄影测量其沉积分布，即心内膜层内的相对血流分布。NADH荧光较高的区域往往受到较低的流量；区域血流-荧光相关性显著。这些结果表明，易缺氧的区域也很难从缺氧中恢复过来，并且区域易缺氧与微循环水平的区域血流异质性高度相关。

We constructed the fluorescence microscope system for imaging of myocardial metabolic activity and blood flow distribution. To measure erythrocyte velocities in microcirculation under in-vivo condition with an intravital videomicroscope, the newly software was developed. A line segment was set along the capillaries in time-sequential videotaped images and then a spatiotemporal image was constructed along that segment. The angle of striped pattern in the spatiotemporal image which reflects the erythrocyte velocity, was estimated to compute erythrocyte velocity vector mapping. We have succeeded in quantitatively evaluating the in-vivo microcirculation with our videomicroscope system and by spatiotemporal image analyzing method. Regional myocardial vulnerability to dysoxia is heterogeneous ; however, the dynamics of regional dysoxia and the dependence of regional dysoxia on flow heterogeneity are not well understood, especially at a microcirculatory level. Thus, we evaluated epimyocardial NADH fluorescence during stepwise changes in oxygenation and made a comparison between NADH fluorescence and flow distributions, resolved into 0.1×0.1- to 0.4×0.4-mm^2 regions the sizes comparable to a microcirculatory unit, which perfused by a single precapillary arteriole. In another hypoxia-perfused hearts showing the stable patchy fluorescence pattern, tritium-labeled desmethylimipramine was infused and its deposition distribution, i.e., relative flow distribution within epimyocardial layers was measured by digital radiography. The region of higher NADH fluorescence tended to receive lower flow ; the regional flow-fluorescence correlation was significant. These results suggest that regions vulnerable to dysoxia are also hard to recover from dysoxia and that regional vulnerability to dysoxia is highly relevant to regional flow heterogeneity at a microcirculatory level.